and that, his chief business in life is to deliver himself from that condition liy means of knowIedRc. The knowledge, t hey taiipht , which avails most in t he st riig- gle for freedom is this: the world of sense |>henomena is an ilhision (m<ii/ii). all real things are ideni ieal in the one supreme sul>stanei\ the soul is part of this real substance, and will ultimately return to the Whole. The real substance is, as Max .Midler remarks, spoken of as a neuter, and in this doctrine "is contained ill Jiucca, whole system of pliilo.sophy " (" .Six Syst<'ius of Indian Philosophy", Loniion, l.SOO, p. (iO). The first, and most important of all truths, then, is that n'ality is one, and that each of us is identical with the All: " Thai art thou is the highest expression of .self-knowl- edge, and the gate to all .s;dutary tnith. Thus, the Hindus, actuated by an ethical, or ascetic, motive, attained a metaphysical formula to which they re- duced all reality.
(2) Greek PhitosopJnj. — ^The first Greek philosophers were .students of nature. They were actuated not by an ethical motive, but by .a. kind of scientific curiosity to know the origins of things. There was no metaphy- sician among the lonians (see Ion-iax School of Phi- losophy). Out of the problem of origins, however, the metaphysical problem was develope<l by the Elcatics and by Heraclitus. These philosophers considered that the explanations of the lonians — tliat the world originated from water orair — were too naive, relied too much on the verdict of the .senses. Consequently, they began to contra,st the real truth which the mind (i-oDs) sees, and the illusory truth (Si^a) which appears to the sen.ses. The Elcatics, on the one hand, asserted tliat the permanent element, which they called Being, alone exists, and that cliange, motion, and multiplicity are illusions. 1 leraelitus, on the other hand, reached the conclusion that what mind reveals is change, which alone is real, while permanency is only apparent, is, in fact, an illusion of the senses. Thas, these thinkers thrust into the foreground the problem of change and permanency. The\" them.selves, were not, however, wholly free from the limitations which confined the earlier lonians to a physicjil view of the problems of philosophy. They form\ilated metaphysical principles of reality, l)ut l)oth in the language which they used and in the mode of thought which they adopted, they seemed to Ixi unable to ri.se above the consideration of matter and material principles. Nevertheless, they did immense service to metaphysics by bringing out clearly the problem of change.
Socrates was primarily an ethical teacher. Still, in laying the foundation of ethics he formulated a theory of knowledge which had immediate application to the problem of metaphysics. 1 le taught that the contrast and apparently irreconcilable contradiction between the verdict of the mind and the deliverance of the senses disappear if we determine the scientific condi- tions of true knowledge. lie held that these condi- tions are summed up in the processes of induction and definition. Ilis conclusion, therefore, is, that out of the data of the senses, which are contingent and par- ticular, we may form concepts, which are the elements of true scientific knowledge. He himself applied the doctrine to ethics.
Plato, the pupil of Socrates, carried the Socratic teaching into the region of metaphysics. If knowledge through conccpt.s is the only true knowledge, it follows, says Plato, that the concejjt represents the only reality, and all the reality, in the object of our knowledge. The sum of the reality of a thing, is therefore the Idea, Corresponding to the internal, or psychological, world of our concepts is not oidy the world of our sense expe- rience (the shadow-world of phenomena), but also the world of Ideas, of which our world of concepts is only a reflection, and the world of sen.se phenomena, a shadow merely. That which makes anything to Ix; what it is, the essence, a,s we should call it, is the Idea of that thing existing in the world above us. In the
"tUng" itself, the phenomenon presented by the
senses, there is a participation of the Idea, limited, dis- figured and deba.'^cd by union with a n(-gat i\c principle of limitation called matter. The metaphysical con- stituents of reality are, therefore, the Ideas as i)ositivo factors and this negative principle. From the Ideas comes all that is positive, permanent, intelligible, eter- nal in the world. From the negative principle come imperfection, negation, change, and liability to di.sso- lution. Thus, profiting by the episteinological doc- trines of Socrates, without losing sight of the antago- nistic teachings of the Elcatics and of Heraclit us, Plato evolved his t heory of Ideas as a metaphysical solution of the problem of change, which had baffled his prede- cessors.
Aristotle also was a follower of Socrates. He was influenced, too, by the theory of Ideas advocate<l by his master, Plato. For, although he rejected that theory, he did so after a study of it which enabled him to view the problem of change in the light of metaphys- ical principles. Like Plato, he accepted the Socratic doctrine that the only true knowledge is knowledge of concepts. Like Plato, too, he inferred from this that the concept must represent the reality jf a thing. But unlike Plato, he made at this point an important dis- tinction. The reality, he taught, which thr concept represents is in the thing which it constitutes, not as an Idea, but as an essence. He considers that the Platonic world of Ideas is a meaningless duplication of things: the world of essences is in, not above, nor beyond, the world of phenomena: there is, conse- quently, no contradiction between sense-experience and infelli'ctual knowledge: the metaphysical princi- ples of things are known by abstraction from those individuating qualities, which are presented in sense- knowledge; the knowledge of them is ultimately empirical, and not to be explained by an intuition which we are alleged to have enjoyed in a previous existence. In the essence of material things Aristotle further distinguished a twofold principle, namely the Form, which is the source of perfection, determinate- ness, activity and of all positive qualities, and the Matter, which is the source of imperfection, indetermi- nation, passivity and of all the limitati-^ns and priva- tions of a thing. Coming now Jo the jorderland of metaphysics and physics, Aristotle defined the nature of causality, and distinguished four supreme kinds of cause. Material, Formal, Efficient and Final (see Cause). In addition to these contributions to the solution of the problem of change, which had, by his- torical evolution, become the central problem of metaphysics, Aristotle contributed to metaphysics a discussion of the nature of Being in general, and drew up a scheme of classification of tilings which is known as his system of Categories. He is least satisfactory in his treatment of the problem of the existence and nature of God, a question in which, as he himself admits, all metaphysical speculation culminates.
After the time of Aristotle, philosophy among the Greeks became centred in problems of human destiny and human conduct. The Stoics and the Epicureans, who were the cliief representatives of this tendency, devoted attention to questions of metaphysics, only in so far as they considered that such questions may iii- fluence human happiness. As a result of this subordi- nation of metaphysics to ethics, the pantheistic mate- rialism of the Stoics and the materialistic momsm of the Epicureans fall far short of the perfection which the doctrines of Plato and Aristotle attained. Gon- teniporaneouslv with the Stoic and Epicurean schools, a new school" of Platonism, generally called Neo- Platonism, interested it.self very much in prolilems of asceticism and mysticism, and, in connexion with these problems, gave a new turn to the drift of meta- physical speculation. The Neo-Platonists, influenced by the monotheism of the Orientals, and, later l)y that of the Christians, took up the task of explaining how